Pen



FIG. 1 is a front elevational view of a pen, showing my new design.

FIG. 2 is a rear elevational view thereof.

FIG. 3 is a right side elevational view thereof.

FIG. 4 is a left side elevational view thereof.

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a top plan view thereof. 

CLAIM The ornamental design for a pen, as shown. 